FIG. 1 is a circuit diagram illustrating the configuration of a discharge tube power supply apparatus according to a related art. The discharge tube power supply apparatus illustrated in FIG. 1 supplies power from an AC power source to a discharge tube used for, for example, a liquid crystal display unit.
In FIG. 1, an external AC power source supplies an AC voltage of 80 to 260 V, which is converted by an AC-DC conversion circuit 1 consisting of a power factor correction circuit into a DC voltage of 380 V. The DC voltage of 380 V from the AC-DC conversion circuit 1 is converted by a DC-DC conversion circuit 2 having an insulated transformer into a DC voltage of 10 to 60 V, which is sent to a secondary side of the electrically insulated transformer.
On the secondary side of the electrically insulated transformer, a DC-AC conversion circuit 3 is arranged to convert the DC voltage of 10 to 60V into an AC voltage of about 700 to 1500 V, which is applied to discharge tubes such as cold cathode tubes 6-1, 6-2, . . . arranged inside a panel 5.
Other related arts are described in, for example, Japanese Unexamined Patent Application Publications No. 2005-71681 and No. H10-50489.